From the prior art as described in DE 690 13 170 T2 a proximity sensor is known, which works with so-termed striplines. Striplines are a particular class of electric waveguides which consist of one or more conductive strips fixed on a dielectric support. Stripline structures can consist for example of conductive strips arranged in one plane. They are often arranged, insulated, in or on a metallic surface. Their field of use is in high-frequency technology and, in that context, within the microwave range. They provide defined impedances in circuits for the transmission, coupling and filtering of high signal frequencies.
Often they are referred to using the English term ‘stripline’ and in many cases also the English term ‘microstrip’, although the latter denotes a particular structural form. In any event striplines are only conducting paths on printed circuits (printed-circuit boards) which are of a size to act as waveguides, and are operated as such. The electric and magnetic fields extend almost exclusively perpendicularly to the propagation direction, as is also the case in coaxial, or two-wire leads. In contrast, however, striplines are only used for short distances within structural groups.
The proximity sensor according to the document DE 690 13 170 T2 makes use of this technology. A proximity sensor is disclosed, which has just one oscillator and just one actuating element, not a rotation angle sensor or a length sensor with two or more oscillators. Correspondingly, in this prior art only the distance of this actuating element from the oscillator is evaluated, but not anything such as a relative movement of a plurality of oscillators around a curve or along a line. The known stripline is either linear (FIGS. 5/6) or of spiral shape (FIGS. 7/8). The purpose of the present invention is to put to use the technology of the known proximity switch for rotation angle sensors and length sensors.